Question

What are the conditions required for sublimation to occur? What kind of particles sublime?

Answer 1

Sublimation process is employed for those solids which convert directly into vapours on heating without converting into liquid phase and the vapours upon cooling give back the solid.

Solid <------> Vapour

Impure samples of naphthalene, anthracene, camphor, benzoic acid, NH₄Cl, HgCl₂, dry ice, salicylic acid, iodine etc. can be purified by this method provided the impurities are non-volatile.